Am Freitag, den 25. November 2011 um 13:12:25 Uhr, schrieb walter harms [off-list ref] in [ref]:

hi,
according to LXR there are several places where the check is >AX25_MAX_DIGIS instead of >=.

any takers ?

nr_route.ndigis is used at 
  nr_call_to_digi(&digi, nr_route.ndigis, nr_route.digipeaters),

Image nr_route.ndigis is 0.

static ax25_digi *nr_call_to_digi(ax25_digi *digi, int ndigis,
        ax25_address *digipeaters)
{
        int i;

        if (ndigis == 0)
                return NULL;

           ################ here we leave

        for (i = 0; i < ndigis; i++) {
                digi->calls[i]    = digipeaters[i];
                digi->repeated[i] = 0;
        }

        digi->ndigi      = ndigis;
        digi->lastrepeat = -1;

        return digi;
}


Image ndigi is 8 (AX25_MAX_DIGIS), as large as nr_route.digipeaters (because it's digipeaters[AX25_MAX_DIGIS]).

we fill the array from i = 0 to i < ndigis (=7) -> 8 times == sizeof(digipeaters)

-> everything is fine with that.

vy 73,
	- Thomas  dl9sau

re,
 wh


Am 25.11.2011 12:22, schrieb walter harms:

quoted

Am 25.11.2011 10:09, schrieb Ralf Baechle:

quoted

nr_route.ndigis is unsigned int so the nr_route.ndigis < 0 expression is
never true and can be dropped.  Doing the nr_ax25_dev_get call later
allows the nr_route.ndigis test to bail out without having to dev_put.

Signed-off-by: Ralf Baechle <redacted>
Cc: Thomas Osterried <redacted>
---
 net/netrom/nr_route.c |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
index 8d7716c..2cf3301 100644
--- a/net/netrom/nr_route.c
+++ b/net/netrom/nr_route.c

@@ -670,12 +670,10 @@ int nr_rt_ioctl(unsigned int cmd, void __user *arg)
 	case SIOCADDRT:
 		if (copy_from_user(&nr_route, arg, sizeof(struct nr_route_struct)))
 			return -EFAULT;
-		if ((dev = nr_ax25_dev_get(nr_route.device)) == NULL)
+		if (nr_route.ndigis > AX25_MAX_DIGIS)
 			return -EINVAL;
-		if (nr_route.ndigis < 0 || nr_route.ndigis > AX25_MAX_DIGIS) {
-			dev_put(dev);
+		if ((dev = nr_ax25_dev_get(nr_route.device)) == NULL)
 			return -EINVAL;
-		}
 		switch (nr_route.type) {
 		case NETROM_NODE:
 			if (strnlen(nr_route.mnemonic, 7) == 7) {

I realy do not know if that matters but some use AX25_MAX_DIGIS as array
and therefore it should be >=AX25_MAX_DIGIS.

struct rose_route_struct {
         rose_address    address;
        unsigned short  mask;
        ax25_address    neighbour;
        char            device[16];
         unsigned char   ndigis;
         ax25_address    digipeaters[AX25_MAX_DIGIS];
  };
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